The invention relates to a sylet for use with an automatic tissue microarrayer. In one embodiment, the invention relates to a stylet which is particularly suited for use in arraying frozen tissues. The invention further relates to molds for generating the stylet.
Tissue microarrays increase the throughput of molecular analyses by simultaneously arraying protein, nucleic acids and other biomolecules. Methods of generating tissue microarrays generally include removing tissue slices or cores from paraffin blocks and re-embedding these. For example, Battifora, Laboratory Investigation, 55:244-248, 1986; and U.S. Pat. No. 4,820, 504, teaches forming multiple tissue samples into rods, bundling the rods into a casing, embedding the encased rods in paraffin and sectioning them. Although the method arrays multiple tissue samples, it is difficult to determine the identity of tissues within the array.
In U.S. Pat. No. 5,002,377, Battifora describes cutting tissue samples into strips, positioning the strips into parallel grooves in a mold, and embedding the strips in paraffin. Embedded strips are stacked, forming an embedded block comprising multiple tissue samples. The method is time consuming and is performed manually.
Automatic tissue microarrayers are described in U.S. Pat. No. 6,103,518, the entirety of which is incorporated herein by reference. The arrayer comprises two hollow needle punches; one for punching a hole in a recipient block comprising paraffin and one for removing a core of paraffin embedded tissue from a sample or donor block. A stylet is used to remove the core of tissue from the donor punch and to push the core of tissue into the hole left in the recipient block. The same, or a different stylet, is used to remove embedding matrix from the recipient punch so that it can be reused. The stylet is in communication with a stylet driver which controls the movement of the stylet.
Although the stylet described in U.S. Pat. No. 6,103,518 can be used to array multiple tissue samples, the stylet functions optimally with paraffin-embeddded samples. However, it is desirable for particular molecular analyses to use frozen tissue samples, particularly in analyses which are geared to examining nucleic acid expression in a tissue sample while maintaining good tissue morphology. It is further desirable in view of the need for high throughput arraying, to provide a stylet that is resistant to breakage, can be reused multiple times, and is inexpensive to manufacture.
The invention provides a stylet for use with an automatic tissue microarrayer which is particularly suitable in the generation of frozen tissue microarrays. The stylet can be used repetitively, greatly increasing the throughput of methods for microarraying frozen tissue. Further, the stylet according to the invention is manufactured from inexpensive plastic materials and is therefore disposable.
In one embodiment, the invention provides a stylet for removing tissue or embedding media from a coring needle and a mold for generating such a stylet. The invention comprises a stylet needle comprising a pushing surface for pushing tissue or embedding media from the coring needle, and a connecting end for connecting the needle to a stylet body. The pushing surface of the stylet needle comprises a material which can maintain a temperature from at least xe2x88x9220xc2x0 to 4xc2x0 C. during the process of removing tissue or embedding material from the coring needle. In one embodiment, the stylet needle comprises stainless steel or a plastic that withstands low temperature impact forces. In a preferred embodiment, the stylet needle is at least partially enclosed within a stylet tube.
In one embodiment, the stylet body comprises a lumen for receiving at least the connecting end of the stylet needle and for preventing rotation of the stylet needle within the stylet body. In a preferred embodiment, the stylet body comprises polypropylene or brass. In another embodiment, the stylet body comprises a stylet base for slideably moving along the length of the stylet needle. In a further embodiment, the stylet comprises a cap for coupling to the connecting end of the stylet needle. In still another embodiment of the invention, the stylet base and stylet cap are separated by a resilient element. In a preferred embodiment, the resilient element is a spring.
In one embodiment, the stylet body comprises an opening for receiving a graspable element. In a preferred embodiment, the stylet comprises a graspable element partially inserted within the opening.
In one embodiment, the invention comprises molds for use in generating the stylet. In a preferred embodiment of the invention, a mold comprises two connectable halves, each half comprising a half mold cavity corresponding in shape to half of at least one external component of the shaft (e.g., the needle, the shaft base, the shaft cap, the graspable element). The mold halves are connectable by connecting elements (e.g., connecting pins, screws, or bolts) which align the mold halves and form a whole mold cavity which provides an impression corresponding in shape to a particular component of the shaft. By injecting the appropriate material into the mold through an opening in communication with the whole mold cavity, the components of the shafts are generated.